KR102071461B1 - Ladar system and method for operating ladar system - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar system and a method of operating the same, which perform stable noise cancellation from radar signals received from fixed and moving objects using a dual loop filter structure with delay compensation. A method of operating a radar system includes an impulse radar transmitting and receiving step of receiving a reflected impulse radar signal fed back from an object with respect to a transmitting impulse radar signal, a first loop filtering step of removing noise from the reflected impulse radar signal and outputting an object impulse signal, transmitting A movement determination step of comparing the impulse radar signal and the object impulse signal to determine the movement of the object; and if determined to be the movement of the object, the second loop filtering to sum the object impulse signal and the delay compensated previous second loop filtering signal; Steps.

Description

Radar system and its operation method {LADAR SYSTEM AND METHOD FOR OPERATING LADAR SYSTEM}

The present invention relates to a radar system for performing stable noise cancellation and a method of operation thereof.

The radar system is a technology for determining search, tracking, and location information of an object generated in a surveillance area using a radio frequency (RF) signal. In a radar system, an RF signal is sent to an object, and the emitted radio wave travels in a straight line to the object and then returns back. The distance, direction, and altitude of the object can be determined by measuring the time of the RF signal reflected back from the object, and the information of the object can be obtained from this information.

However, the RF signal reflected back from the object may include a noise signal added in various paths or an instantaneous noise signal in addition to the signal reflected from the object.

Such noise signals may cause an error in acquiring information of an object, and may even recognize the noise signals as an object.

Korean Unexamined Patent Publication No. 2012-0080064

The technical problem to be solved by the present invention is to provide a radar system and a method of operating the same by using a dual loop filter structure with delay compensation to perform a stable noise removal from the radar signal received from a fixed object and a moving object It is.

The operation method of the radar system for solving the technical problem to be achieved by the present invention comprises: an impulse radar transmission and reception step of receiving a reflected impulse radar signal fed back from the object to the transmission impulse radar signal; A first loop filtering step of outputting an object impulse signal by removing noise from the reflected impulse radar signal; A movement determining step of comparing the transmission impulse radar signal and the object impulse signal to determine the movement of the object; And a second loop filtering step of adding the object impulse signal and the delay compensated previous second loop filtering signal when it is determined that the object is moved.

In the present invention, the second loop filtering step includes: obtaining a position of the current object impulse signal from a current object impulse signal including additional noise by using the transmission impulse radar signal; Delay compensating a position of a previous object impulse signal included in the previous second loop filtering signal to a position of the current object impulse signal; And summing the current object impulse signal including the additional noise and the delay compensated second previous loop filtering signal.

In the present invention, the second loop filtering step includes: summing a current object impulse signal including the additional noise and the delayed second previous loop filtering signal when the object is stopped. It features.

The radar system for solving the technical problem to be achieved by the present invention includes an impulse radar transceiver for receiving a reflected impulse radar signal fed back from the object to the transmission impulse radar signal; A first loop filtering unit which removes noise from the reflected impulse radar signal and outputs an object impulse signal; And comparing the transmission impulse radar signal and the object impulse signal to determine the movement of the object, and when the movement of the object is determined, adds the object impulse signal and a delay compensated previous second loop filtering signal. It characterized in that it comprises a; 2 loop filtering unit.

In the present invention, the second loop filtering unit obtains the position of the current object impulse signal from the current object impulse signal including additional noise by using the transmission impulse radar signal, and applies the second loop filtering signal to the previous second loop filtering signal. Delay-compensate a position of an included previous object impulse signal to a position of the current object impulse signal, and add the current object impulse signal including the additional noise and the delay compensated previous second loop filtering signal. do.

The second loop filtering unit, when the object is stationary, adds the current object impulse signal including the additional noise and the delayed previous second loop filtering signal.

As described above, according to the present invention, it is possible to stably remove noise from a radar signal received from a fixed object and a moving object by using a dual loop filter structure including delay compensation.

1 is a block diagram showing the configuration of a radar system according to an embodiment of the present invention.
FIG. 2 is a detailed block diagram of the signal processor 200 of FIG. 1.
3 is a waveform diagram illustrating noise cancellation to which delay compensation is not applied when moving an object.
4 is a waveform diagram illustrating noise removal by applying delay compensation when moving an object.
5 is a waveform diagram illustrating noise removal when an object is fixed.
6 is a flowchart illustrating a method of operating a radar system according to an exemplary embodiment.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments set forth below, but may be embodied in many different forms and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. . The embodiments set forth below are provided to make the disclosure of the present invention complete, and to fully inform the scope of the invention to those skilled in the art. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, and in the following description with reference to the accompanying drawings, the same or corresponding components will be given the same reference numerals and redundant description thereof will be omitted. Let's do it.

1 is a block diagram showing the configuration of a radar system according to an embodiment of the present invention.

Referring to FIG. 1, the radar system 10 includes a transmitter 100 including a transmit antenna 110, a receiver 200 including a receive antenna 210, a signal processor 300, a distance estimator 400, and It includes a motion detector 500.

The transmitter 100 outputs a transmission impulse radar signal T (t) through the transmission antenna 110. The receiver 200 receives the reflected impulse radar signal R (t) reflected from the object. Here, the transmitter 100 and the receiver 200 may be integrally formed or configured separately, and in the present embodiment, it is assumed that the transmitter 100 and the receiver 200 are configured separately. The transmission impulse radar signal T (t) passes through the transmission antenna 110 in a straight line to the object, and then returns by reflecting (reflecting impulse radar signal R (t)) from the object.

The signal processor 300 removes the noise signal included in the reflected impulse radar signal R (t) by using the transmission impulse radar signal T (t). The reflected impulse radar signal R (t) includes an object impulse signal and a noise signal purely reflected from the object. Here, the noise signal may be a noise signal generated in various paths, an instantaneous noise signal, a clutter, or the like. The signal processor 300 removes a noise signal from a fixed impulse radar signal R (t) received from a fixed object and a moving object by using a dual loop filter structure including delay compensation and outputs an object impulse signal. do.

2 is a detailed block diagram of the signal processor 200 of FIG. 1. Referring to FIG. 2, the signal processor 300 includes a first loop filter 310 and a second loop filter 320.

The first loop filter 310 removes noise from the currently input reflected impulse radar signal R (t) by summing the currently input reflected impulse radar signal R (t) and the delayed previous first loop filtering signal. The object impulse signal S '(t) is output. The first loop filter 310 includes a first multiplier 311, a first adder 312, a delay 313, a second multiplier 314, and a subtractor 315.

The first multiplier 311 multiplies the currently input reflection impulse radar signal R (t) by the weight 1-α. The weight can be arbitrarily set here. The first adder 312 adds the delayed previous noise signal C (t-1) multiplied by the output of the first multiplier 311 and the weight α to output the current noise signal C (t). . Here, the previous noise signal C (t-1) is delayed for a predetermined time through the delay unit 313 and multiplied by the weight α through the second multiplier 314. The first adder 312 iteratively repeats the current reflected impulse radar signal R (t) multiplied by the weight 1-α and the delayed previous noise signal C (t-1) multiplied by the weight α. The addition outputs the current noise signal C (t). The subtractor 315 subtracts the current noise signal C (t) from the current reflection impulse radar signal R (t), and thus the current object impulse signal S 'from which the current noise signal C (t) has been removed. (t))

Although the noise signal is removed through the first loop filter 310, the object impulse signal S ′ (t) output from the first loop filter 310 includes an additionally generated noise signal or an incompletely removed noise signal. It may be. Therefore, the additional noise signal may be removed through the second loop filter 320.

The second loop filter 320 compares the transmission impulse radar signal T (t) and the current object impulse signal S '(t) to determine the movement of the object, and if it is determined that the object has moved, the current object. Perform second loop filtering S (t) that sums the impulse signal S '(t) and the delay compensated previous second loop filtering signal d (t), and determines that the object is stationary. In this case, the second loop filtering S (t) summing the current object impulse signal S '(t) and the delayed previous second loop filtering signal S (t-1) is performed.

The second loop filter 320 includes a first multiplier 321, an adder 322, a delay 323, a delay compensator 324, and a second multiplier 325.

The first multiplier 321 multiplies the current object impulse signal S '(t) with the additional noise signal by the weight 1-β. The weight can be arbitrarily set here. The adder 322 sums the output of the first multiplier 321 and the delay-compensated previous second loop filtering signal d (t) multiplied by the weight β, or the output of the first multiplier 321. The delayed previous second loop filtering signal S (t-1) multiplied by the weight β is summed and output.

Here, the delay compensator 324 compares the transmission impulse radar signal T (t) and the object impulse signal S '(t) to determine the movement of the object. As shown in FIG. 3, when the object moves, the position of the object impulse signal among the current object impulse signal S ′ (t) including the additional noise signal is determined by the previous second loop filtering signal S (t-1). It is different from the position of the object impulse signal included in the. In this case, when the loop filtering is performed, the strength of the actual object impulse signal is greatly reduced, so that it is difficult to obtain an accurate object impulse signal. Therefore, the second loop filter 320 divides the case where the object moves and the case where the object is stationary to perform different noise signal removal.

The delay compensator 324 compares a time difference by comparing an object pulse signal among a transmission impulse radar signal T (t) and a current object pulse signal S '(t) including an additional noise signal to determine an object movement. If is greater than or equal to the reference value it can be determined that the object has moved, and if the time difference is less than the reference value can be determined that the object is stationary.

First, the operation of the second loop filtering unit 320 when it is determined that the object has moved will be described.

The delay unit 323 delays and outputs the previous second loop filtering signal (S (t-1)). The delay compensator 324 uses the transmission impulse radar signal T (t) on the assumption that the position of the current object impulse signal is similar to the position of the previous object impulse signal. (t)) acquires the position of the current object impulse signal, and delay-compensates the position of the previous object impulse signal included in the delayed previous second loop filtering signal S (t-1) to the current object impulse position Output d (t). Here, the position of the previous object impulse signal can be found by using a cross correlation function, and the delay compensator 324 delay-compensates the position of the previous object impulse signal to the current object impulse position and outputs (d ( t)). 4 illustrates an example of delay compensation of a position of a previous object impulse signal included in a delayed previous second loop filtering signal S (t-1) to a current object impulse position. When the object moves, only the impulse signal position of the moving object is corrected except the noise signal, so that the object can be continuously detected without distortion of the object impulse signal and the noise signal can be removed.

The second multiplier 325 multiplies the delay compensated second loop filtering signal d (t) by the weight β. The adder 322 adds the current object impulse signal S '(t) including the additional noise signal multiplied by the weight (1-β) and the delay compensated second loop filtering signal d (t) to add the additional noise signal. The final object impulse signal S (t) from which the noise is removed is output. 4 is a waveform diagram illustrating second loop filtering when an object is moved. The adder 322 iteratively adds the current object impulse signal S '(t) including the additional noise signal multiplied by the weight 1-β and the delay compensated second loop filtering signal d (t). This outputs the final object impulse signal S (t) from which the additional noise signal is removed.

Next, the operation of the second loop filtering unit 320 in the case of determining that the object is stationary will be described.

The delay unit 323 delays and outputs the previous second loop filtering signal (S (t-1)). When the object is stopped, the delay compensator 324 bypasses the output of the delay unit 323, that is, the delayed second loop filtering signal S (t-1), without performing delay compensation.

The second multiplier 325 multiplies the delayed second loop filtering signal S (t-1) by the weight β. The adder 322 adds the current object impulse signal S '(t) including the additional noise signal multiplied by the weight 1-β and the delayed second loop filtering signal S (t-1). The final object impulse signal S (t) from which the noise is removed is output. 5 shows a waveform diagram illustrating second loop filtering when an object is stationary. The adder 322 iteratively adds the current object impulse signal S '(t) and the delayed second loop filtering signal S (t-1) including the additional noise signal multiplied by the weight 1-β. This outputs the final object impulse signal S (t) from which the additional noise signal is removed.

If the first loop filter 310 is used to find and remove the noise signal, the second loop filter 320 may be used to smooth the signal. This eliminates irregular and instantaneous noise signals. In addition, better smoothing and noise rejection results are obtained for moving objects.

The distance estimator 400 may estimate the distance r of the object based on the similarity between the transmission impulse radar signal T (t) and the reflected impulse radar signal R (t) reflected from the object. The distance estimator 400 measures a time difference between the transmission impulse radar signal T (t) and the reflected impulse radar signal R (t) using a cross correlation function, and based on the object The distance r can be estimated.

The motion detector 500 may detect the movement of the object based on the estimated distance information.

As described above, noise reduction may be stably performed from the radar signals received from the fixed object and the moving object by using a dual loop filter structure including delay compensation. This enables accurate distance and motion detection of the object.

6 is a flowchart illustrating a method of operating a radar system according to an exemplary embodiment. The method of operating the radar system according to the present invention may be performed in the radar system 10 with the help of peripheral components as shown in FIG. 1. In the following description, portions overlapping with the description of FIGS. 1 to 5 will be omitted.

Referring to FIG. 6, the radar system 10 performs an operation S100 of receiving an impulse radar signal R (t) reflected from an object with respect to the transmission impulse radar signal T (t).

When receiving the impulse radar signal R (t) reflected from the object, the radar system 10, the signal processing unit 300 uses the transmission impulse radar signal T (t), the reflection impulse radar signal R (t) In operation S200, the first loop filtering outputting the object impulse signal S ′ (t) from which the noise signal (C (t)) is removed may be performed. (t)) includes an object impulse signal and a noise signal that are purely reflected from an object, where the noise signal may be a noise signal generated in various paths, a noise signal generated instantaneously, a clutter, or the like.

Although the noise signal is removed through the first loop filtering, the output object impulse signal S ′ (t) may include an additionally generated noise signal or an incompletely removed noise signal. Therefore, the second loop filtering may be performed to remove the additional noise signal.

When the first loop filtering operation is completed, the radar system 10 compares the transmission impulse radar signal T (t) and the current object impulse signal S '(t) to determine the movement of the object (S300). Perform When the object moves, the position of the object impulse signal among the current object impulse signal S '(t) including the additional noise signal is determined by the position of the object impulse signal included in the previous second loop filtering signal S (t-1). Different from the location. In this case, when the loop filtering is performed, the strength of the actual object impulse signal is greatly reduced, so that it is difficult to obtain an accurate object impulse signal. Therefore, in case of the second loop filtering, different noise signals are removed by dividing into the case where the object moves and the case where the object is stationary. The radar system 10 compares the object pulse signal among the transmission impulse radar signal T (t) and the current object pulse signal S '(t) including the additional noise signal to determine the movement of the object. When the reference value is greater than or equal to the reference value, it is determined that the object has moved, and when the time difference is less than the reference value, it may be determined that the object is stationary.

If the radar system 10 determines that the object has moved, it performs second loop filtering that sums the current object impulse signal S '(t) and the delay compensated previous second loop filtering signal d (t). And if it is determined that the object is stationary, performing second loop filtering summing the current object impulse signal S '(t) and the delayed previous second loop filtering signal S (t-1) (S400). ).

If it is determined that the object has moved, the radar system 10 includes additional noise using the transmit impulse radar signal T (t) on the assumption that the position of the current object impulse signal will be similar to that of the previous object impulse signal. Acquire the position of the current object impulse signal among the current object impulse signal S '(t), and determine the position of the previous object impulse signal included in the delayed previous second loop filtering signal S (t-1). Delay compensation to the object impulse position to output (d (t)). Here, the position of the previous object impulse signal can be found by using a cross correlation function, and the delay compensator 324 delay-compensates the position of the previous object impulse signal to the current object impulse position and outputs (d ( t)). When the object moves, only the impulse signal position of the moving object is corrected except the noise signal, so that the object can be continuously detected without distortion of the object impulse signal and the noise signal can be removed. The radar system 10 sums the current object impulse signal S '(t) including the additional noise signal multiplied by the weight 1-β and the delay compensated second loop filtering signal d (t). Outputs the final object impulse signal S (t) from which additional noise is removed. The radar system 10 iteratively repeats the current object impulse signal S '(t) containing the additional noise signal multiplied by the weight 1-β and the delay compensated second loop filtering signal d (t). The addition outputs the final object impulse signal S (t) from which the additional noise signal is removed.

If it is determined that the object is stationary, the radar system 10 does not perform delay compensation, but rather delays the current object impulse signal S '(t) with the additional noise signal multiplied by the weight 1-β. The two loop filtering signal S (t-1) is added to output the final object impulse signal S (t) from which additional noise is removed. The radar system 10 iteratively repeats the current object impulse signal S '(t) and the delayed second loop filtering signal S (t-1) including the additional noise signal multiplied by the weight 1-β. The addition outputs the final object impulse signal S (t) from which the additional noise signal is removed.

The radar system 10 then estimates and estimates the distance r of the object based on the similarity between the transmit impulse radar signal T (t) and the reflected impulse radar signal R (t) reflected from the object. The movement of the object may be detected based on the received distance information.

Various embodiments of the invention do not limit the scope of the invention in any way. For brevity of description, descriptions of conventional electronic configurations, control systems, software, and other functional aspects of the systems may be omitted. In addition, the connection or connecting members of the lines between the components shown in the drawings are illustrative of the functional connection and / or physical or circuit connections by way of example, in the actual device replaceable or additional various functional connection, physical connection Or circuit connections. In addition, unless there is a specific mention such as "essential", "important" and the like may not be a necessary component for the practice of the present invention.

In the specification (particularly in the claims) of the present invention, the use of the term “above” and similar indicating terminology may correspond to both the singular and the plural. In addition, in the present invention, when the range is described, it includes the invention to which the individual values belonging to the range are applied (when there is no description thereof), and each individual value constituting the range is described in the detailed description of the invention. Same as

If the steps constituting the method according to the invention are not explicitly stated or contrary to the steps, the steps may be performed in a suitable order. The present invention is not necessarily limited to the description order of the above steps. The use of all examples or exemplary terms (eg, etc.) in the present invention is merely for describing the present invention in detail and is not limited by the claims, and thus the scope of the present invention is limited by the examples or exemplary terms. It doesn't happen. Also, one of ordinary skill in the art appreciates that various modifications, combinations and changes can be made in accordance with design conditions and factors within the scope of the appended claims or their equivalents.

Accordingly, the spirit of the present invention should not be limited to the above-described embodiments, and all the scope equivalent to or equivalent to the scope of the claims as well as the claims to be described below are within the scope of the spirit of the present invention. Will belong to.

10: radar system 100: transmitter
200: receiver 300: signal processor
310: first loop filter 320: second loop filter
400 distance estimator 500: motion detector

Claims (6)

delete delete delete An impulse radar transceiver for receiving a reflected impulse radar signal fed back from an object with respect to a transmission impulse radar signal;
A first loop filtering unit which removes noise from the reflected impulse radar signal and outputs an object impulse signal;
A second that compares the transmission impulse radar signal and the object impulse signal to determine the movement of the object, and adds the object impulse signal and a delay compensated previous second loop filtering signal when it is determined that the object is moved; Radar system comprising a; loop filtering unit. The method of claim 4, wherein the second loop filtering unit,
The position of the current object impulse signal is obtained from the current object impulse signal including additional noise by using the transmission impulse radar signal, and the position of the previous object impulse signal included in the delayed previous second loop filtering signal is obtained. Generate the delay compensated previous second loop filtering signal that is delay compensated to the position of an impulse signal, and sum the current object impulse signal containing the additional noise and the delay compensated previous second loop filtering signal; Radar system. The method of claim 5, wherein the second loop filtering unit,
And when the object is stationary, summing the current object impulse signal containing the additional noise and the delayed previous second loop filtering signal.

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